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Pattern randomness aftereffect.

Yamada Y, Kawabe T, Miyazaki M - Sci Rep (2013)

Bottom Line: Perceived randomness decreased (increased) following adaptation to high (low) physical randomness (Experiment 1).Our data were consistent with a model assuming filter-rectify-filter processing for orientation inputs.Thus, we infer that neural processing for orientation grouping/segregation underlies the perception of pattern randomness.

View Article: PubMed Central - PubMed

Affiliation: 1] Research Institute for Time Studies, Yamaguchi University, Yamaguchi, Yamaguchi, Japan [2].

ABSTRACT
Humans can easily discriminate a randomly spaced from a regularly spaced visual pattern. Here, we demonstrate that observers can adapt to pattern randomness. Following their adaption to prolonged exposure to two-dimensional patterns with varying levels of physical randomness, observers judged the randomness of the pattern. Perceived randomness decreased (increased) following adaptation to high (low) physical randomness (Experiment 1). Adaptation to 22.5°-rotated adaptor stimuli did not cause a randomness aftereffect (Experiment 2), suggesting that positional variation is unlikely to be responsible for the pattern randomness perception. Moreover, the aftereffect was not selective to contrast polarity (Experiment 3) and was not affected by spatial jitter (Experiment 4). Last, the aftereffect was not affected by adaptor configuration (Experiment 5). Our data were consistent with a model assuming filter-rectify-filter processing for orientation inputs. Thus, we infer that neural processing for orientation grouping/segregation underlies the perception of pattern randomness.

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(a, b) Schematic diagrams of how the stimuli were presented in (a) low-randomness and (b) high-randomness conditions. (c) The results of Experiment 1. Larger x and y values represent larger physical randomness of the adaptor stimulus and larger matched randomness of the test stimulus, respectively. The dashed line represents the physical randomness value of the test stimulus (i.e., with middle physical randomness) that was fixed through experiments. The error bars denote the standard errors of the means (n = 6).
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f2: (a, b) Schematic diagrams of how the stimuli were presented in (a) low-randomness and (b) high-randomness conditions. (c) The results of Experiment 1. Larger x and y values represent larger physical randomness of the adaptor stimulus and larger matched randomness of the test stimulus, respectively. The dashed line represents the physical randomness value of the test stimulus (i.e., with middle physical randomness) that was fixed through experiments. The error bars denote the standard errors of the means (n = 6).

Mentions: In Experiment 2, we examine whether models other than the FRF process, such as a model based on a relative positional relationship of dots (e.g., distance to the nearest neighbour; Dnn)25 or a model based on an autocorrelation function of patterns26, can explain an individual's adaptation to pattern randomness. We focused on the effect of the rotation of the adaptors on pattern regularity/randomness adaptation. Here, the ‘rotation’ means a change in orientation of a whole pattern (Figure 2a shows examples of a pattern), not a continuous rotational pattern motion. We considered an FRF process that consisted of an isotropic first-order filter defined by the differences of Gaussian function and a vertically oriented second-order filter defined by a sinusoidal grating that was windowed by a two-dimensional circular Gaussian function (Figure 1a). If the FRF process were involved in the pattern randomness aftereffect, the adaptation to rotated adaptors would not cause any aftereffects with non-rotated test stimuli because the FRF process adapting to the rotated pattern has a different orientation tuning to the FRF process for a non-rotated pattern. In Experiment 3, we examined whether the adaptation could occur independent of contrast polarity. Furthermore, to provide evidence on the dissociation of findings between current and previous studies (i.e., bidirectional vs. unidirectional aftereffect), we tested the effect of jittering on the pattern randomness aftereffect (Experiment 4). In some conditions in these experiments, we presented a control adaptor with middle randomness on the contralateral side of a critical adaptor having high randomness. In this situation, it was logically possible that the visual system might adapt to a weak regularity in the control adaptor without having any adaptation to randomness in the critical adaptor. Even under this scenario, a test stimulus that follows the critical adaptor with high randomness is judged to be more regular than a test stimulus that follows the control adaptor with middle randomness when the test stimuli have the same degree of randomness. In this way, with the paradigm having the two adaptors, we could not exclude the alternative interpretation that the visual system adapts to pattern regularity only24. To rule out the involvement of adaptation to a weak regularity in the control adaptor, in Experiment 5 we stopped using a control adaptor, and investigated whether the adaptation to pattern randomness was observed even when only a critical adaptor with high or low randomness was presented.


Pattern randomness aftereffect.

Yamada Y, Kawabe T, Miyazaki M - Sci Rep (2013)

(a, b) Schematic diagrams of how the stimuli were presented in (a) low-randomness and (b) high-randomness conditions. (c) The results of Experiment 1. Larger x and y values represent larger physical randomness of the adaptor stimulus and larger matched randomness of the test stimulus, respectively. The dashed line represents the physical randomness value of the test stimulus (i.e., with middle physical randomness) that was fixed through experiments. The error bars denote the standard errors of the means (n = 6).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3795352&req=5

f2: (a, b) Schematic diagrams of how the stimuli were presented in (a) low-randomness and (b) high-randomness conditions. (c) The results of Experiment 1. Larger x and y values represent larger physical randomness of the adaptor stimulus and larger matched randomness of the test stimulus, respectively. The dashed line represents the physical randomness value of the test stimulus (i.e., with middle physical randomness) that was fixed through experiments. The error bars denote the standard errors of the means (n = 6).
Mentions: In Experiment 2, we examine whether models other than the FRF process, such as a model based on a relative positional relationship of dots (e.g., distance to the nearest neighbour; Dnn)25 or a model based on an autocorrelation function of patterns26, can explain an individual's adaptation to pattern randomness. We focused on the effect of the rotation of the adaptors on pattern regularity/randomness adaptation. Here, the ‘rotation’ means a change in orientation of a whole pattern (Figure 2a shows examples of a pattern), not a continuous rotational pattern motion. We considered an FRF process that consisted of an isotropic first-order filter defined by the differences of Gaussian function and a vertically oriented second-order filter defined by a sinusoidal grating that was windowed by a two-dimensional circular Gaussian function (Figure 1a). If the FRF process were involved in the pattern randomness aftereffect, the adaptation to rotated adaptors would not cause any aftereffects with non-rotated test stimuli because the FRF process adapting to the rotated pattern has a different orientation tuning to the FRF process for a non-rotated pattern. In Experiment 3, we examined whether the adaptation could occur independent of contrast polarity. Furthermore, to provide evidence on the dissociation of findings between current and previous studies (i.e., bidirectional vs. unidirectional aftereffect), we tested the effect of jittering on the pattern randomness aftereffect (Experiment 4). In some conditions in these experiments, we presented a control adaptor with middle randomness on the contralateral side of a critical adaptor having high randomness. In this situation, it was logically possible that the visual system might adapt to a weak regularity in the control adaptor without having any adaptation to randomness in the critical adaptor. Even under this scenario, a test stimulus that follows the critical adaptor with high randomness is judged to be more regular than a test stimulus that follows the control adaptor with middle randomness when the test stimuli have the same degree of randomness. In this way, with the paradigm having the two adaptors, we could not exclude the alternative interpretation that the visual system adapts to pattern regularity only24. To rule out the involvement of adaptation to a weak regularity in the control adaptor, in Experiment 5 we stopped using a control adaptor, and investigated whether the adaptation to pattern randomness was observed even when only a critical adaptor with high or low randomness was presented.

Bottom Line: Perceived randomness decreased (increased) following adaptation to high (low) physical randomness (Experiment 1).Our data were consistent with a model assuming filter-rectify-filter processing for orientation inputs.Thus, we infer that neural processing for orientation grouping/segregation underlies the perception of pattern randomness.

View Article: PubMed Central - PubMed

Affiliation: 1] Research Institute for Time Studies, Yamaguchi University, Yamaguchi, Yamaguchi, Japan [2].

ABSTRACT
Humans can easily discriminate a randomly spaced from a regularly spaced visual pattern. Here, we demonstrate that observers can adapt to pattern randomness. Following their adaption to prolonged exposure to two-dimensional patterns with varying levels of physical randomness, observers judged the randomness of the pattern. Perceived randomness decreased (increased) following adaptation to high (low) physical randomness (Experiment 1). Adaptation to 22.5°-rotated adaptor stimuli did not cause a randomness aftereffect (Experiment 2), suggesting that positional variation is unlikely to be responsible for the pattern randomness perception. Moreover, the aftereffect was not selective to contrast polarity (Experiment 3) and was not affected by spatial jitter (Experiment 4). Last, the aftereffect was not affected by adaptor configuration (Experiment 5). Our data were consistent with a model assuming filter-rectify-filter processing for orientation inputs. Thus, we infer that neural processing for orientation grouping/segregation underlies the perception of pattern randomness.

Show MeSH
Related in: MedlinePlus